a) Field of Invention
This invention relates to metallic powders suitable for manufacturing electrodes adapted for producing hydrogen by water electrolysis. More particularly, the invention is concerned with the manufacture of nanocrystalline (FCC) powders of alloys of nickel and molybdenum by high energy mechanical deformation, said powders having a high electrocatalytic activity for hydrogen evolution.
b) Description of Prior Art
It is known that a successful electrolysis of alkaline water can be achieved using an electrode consisting of an alloy of an element selected from the group consisting of nickel, cobalt, iron and one from Mo, W, V. Such an electrode is normally made of an alloy of nickel and molybdenum, wherein nickel is used in predominant amount.
U.S. Pat. No. 4,358,475 issued on Nov. 9, 1982 to the British Petroleum Company Limited discloses a complicated method of producing metal electrodes by coating a substrate with a homogeneous solution of compounds of iron, cobalt or nickel and compounds of molybdenum, tungsten or vanadium. The coated substrate is thereafter thermally decomposed to give an oxide-coated substrate which is then cured in a reducing atmosphere at elevated temperature. This method produces good electrodes but is obviously complicated, expensive to achieve and time consuming. The same technology is also disclosed in the following publications:
Int. J. Hydrogen Energy, Vol.7, No. 5, pp. 405-410, 1987, D. E. Brown et al.
Electrochimica Acta, Vol. 29, No. 11, pp. 1551-1556, 1984, D. E. Brown et al.
On the other hand, alloys of nickel and titanium and of nickel and niobium in the form of amorphous powders have been produced by mechanical alloying in a laboratory ball/mill mixer, as disclosed in:
Appl. Phys. Lett. 49(3), 21 July 1986, pp. 146-148, Ricardo B. Schwarz et al.
E. Hellstern et al., at a Symposium on "Multicomponent Ultrafine Microstructures" held in Boston, Mass. on Nov. 30, 1988, discloses the preparation of nanocrystalline AlRu by ball milling. The process is essentially restricted to Ru and AlRu and there is no disclosure of the usefulness of the product obtained thereby.
Finally, A. W. Weeber et al. review the production of amorphous alloys by ball milling in: Physica B, Vol. 153, pp. 93-135, 1988, A. W. Weeber and H. Bakker.
The prior art is therefore completely devoided of any disclosure of electrodes of alloys which can be used to produce hydrogen, and which have been manufactured by mechanical alloying.
It is an object of the present invention to provide metallic powders which can be used with advantage to produce electrodes that may be utilized in the electrolytic production of hydrogen.
It is another object of the present invention to provide metallic powders having a unique morphology and microstructure, which differ from those produced by other techniques and which can be used with advantage to manufacture hydrogen producing electrodes.
It is another object of the present invention to manufacture low cost cathodes which can be used to produce hydrogen by means of a simple technique of fabrication without requiring chemical, thermic or electrochemical treatment of the active materials.
It is another object of the present invention to provide a material for the manufacture of electrodes which requires no substrates.